const watermark: any = {}

const setWatermark = (text: string, sourceBody: HTMLElement) => {
  const id: string =
    Math.random() * 10000 +
    '-' +
    Math.random() * 10000 +
    '/' +
    Math.random() * 10000

  if (document.getElementById(id) !== null) {
    const element: Document = document.getElementById(id) as any
    document.body.removeChild(element)
  }

  const can = document.createElement('canvas')
  can.width = 200 //设置水印之间的左右间距
  can.height = 160 //设置水印之间的上下间距

  const cans: any = can.getContext('2d')
  cans.rotate((-20 * Math.PI) / 180)
  cans.font = '15px Vedana'
  cans.fillStyle = 'rgba(0, 0, 0, .5)'
  cans.textAlign = 'left'
  cans.textBaseline = 'Middle'
  cans.fillText(text, can.width / 20, can.height)

  const water_div = document.createElement('div')
  water_div.id = id
  water_div.className = 'watermarkClass'
  water_div.style.pointerEvents = 'none'
  water_div.style.background =
    'url(' + can.toDataURL('image/png') + ') left top repeat'
  if (sourceBody) {
    water_div.style.width = '100%'
    water_div.style.height = '100%'
    water_div.style.position = 'fixed'
    water_div.style.zIndex = '100000'
    sourceBody.appendChild(water_div)
  } else {
    water_div.style.top = '3px'
    water_div.style.left = '0px'
    water_div.style.position = 'absolute'
    water_div.style.zIndex = '100000'
    water_div.style.width = document.documentElement.clientWidth + 'px'
    water_div.style.height = document.documentElement.clientHeight + 'px'
    document.body.appendChild(water_div)
  }

  return id
}

/**
 *  该方法只允许调用一次
 *  @param:
 *  @text == 水印内容
 *  @sourceBody == 水印添加的位置，不传就是body
 * */
watermark.set = (text: string, sourceBody: HTMLElement) => {
  const domArr = Array.from(document.getElementsByClassName('watermarkClass'))
  for (let i = 0; i < domArr.length; i++) {
    const element = domArr[i]
    // element.parentNode.removeChild(element);
    element.remove()
  }
  if (text == '') {
    return
  }
  setWatermark(text, sourceBody)
}

export { watermark }
